Does the son's ability to dispose of the gifted item affect the father's right to revocation?

Primary text

The second condition is that the gifted item must remain in a state where the son has the right to dispose of its corpus (ownership). If the son uses a female slave for procreation (istilad), the father cannot revoke the gift because the ownership established therein cannot be transferred to anyone other than its master. If the son pledges the item as a mortgage (rahn), or if he becomes bankrupt and restricted from disposition, the father cannot revoke, as this would invalidate the rights of others. If the impediment to disposition is removed, the father may revoke because the son's ownership was not extinguished, only a restriction on disposal occurred, which is removed when the underlying cause is gone. Writing an agreement for manumission (kitaba) is treated similarly by those who do not permit the sale of a mukatab (a slave contracted for freedom); this is the position of Al-Shafi'i and a group of scholars. Those who permit the sale of a mukatab treat him like a lessee or someone whose marriage contract is being dissolved. Regarding disposal in promise (tadbir), the sound opinion is that it does not prevent sale and thus does not prevent revocation. If it is held that it prevents sale, it prevents revocation. Any disposition that does not prevent the son from disposing of the corpus, such as a bequest, a gift before receipt (if required), sexual intercourse, marriage, tenancy (ijarah), kitaba, tadbir (if sale is permitted), sharecropping, partnership, or conditional manumission, does not prevent revocation because the son retains the right over the corpus. If the father revokes while the prior disposition is binding (like marriage, tenancy, or kitaba), that disposition remains intact because the son could not void it, and thus neither can the recipient of the revoked gift. If the prior disposition was revocable (like a bequest or gift before receipt), it becomes void because the son had the right to void it. Regarding tadbir and conditional manumission, their effect ceases in relation to the father, and their effect returns if the item reverts to the son. If the son sells the item and retains an option to revoke (due to condition, defect in the counter-value, etc.), revocation by the father is prevented because revocation implies voiding the son's ownership of the substitute, which was not established by the father. If the son gifts the item to his own son, the father cannot revoke because his revocation would void the ownership of his grandson.